The main objective of the study is to examine the impact of drug abuse treatment on subsequent criminal behavior of opiate users. Information for the study is provided by two automated data bases. One file consists of all opiate drug abuse clients serviced by the Los Angeles County Drug Abuse Program; the second consists of the entire State of California Arrest Citation and Offender Disposition file maintained by the Bureau of Criminal Statistics. Both data bases cover the same four-year period. An important aspect of the study is that it will for the first time integrate on a large scale clients in opiate treatment programs (e.g., over 15,000 cases) with all official criminal justice information. In this way, then, the actual magnitude of this particular group's criminal activity can be assessed with a sample size which is large enough to control for many important research issues. The analysis is designed to include the following comparisons: between groups, within groups, and between treatment populations. The first general category involves the comparison between the treated drug abusers, the general population, and the offender population. The second category of comparison utilizes an Offender-Based Transaction system and concentrates on comparisons between types of offenders and their various dispositions within the criminal justice system on the basis of an addict-no-addict distinction. The third comparison is within the drug treatment system and examines the impact of various programs as related to reduction in criminal activity.